论文部分内容阅读
为了解风化壳中离子交换相稀土元素的特征,对广西某地花岗岩风化壳剖面样品进行了X射线衍射及主量、稀土元素地球化学特征的研究.剖面自上而下可划分为腐殖土层(A1)、亚粘土层(A2)、网纹状风化层(B1)和全风化层(B2);自A1至B2,粘土矿物的含量和化学风化蚀变指数快速降低;与母岩相比A1、A2、B1中全相Ce、Nd和HREE相对富集,B2中全相稀土与母岩特征相似,所有样品的离子交换相HREE亏损,Y相对富集;离子交换相轻、重稀土一起富集在B2中.据此推测,花岗岩中褐帘石、榍石等易风化的稀土矿物为离子交换相稀土提供了主要的物源,锆石、磷钇矿等难风化的稀土矿物的残留及表生稀土矿物的形成使全相HREE相对富集;离子交换相轻、重稀土元素的分馏程度随风化程度的增加而变化.
In order to understand the characteristics of rare earth elements in the ion exchange phase of weathering crust, the X-ray diffraction and the main quantitative and geochemical characteristics of the rare earth elements of the granite weathering crust profile in a certain area of Guangxi were studied.The profile can be divided into humus (Al), sub-clay (A2), reticular weathered (B1) and fully weathered (B2). From A1 to B2, the content of clay minerals and chemical weathering alteration index decreased rapidly, All phases are enriched in all phases Ce, Nd and HREE in A1, A2 and B1. The characteristics of all-phase rare earth in B2 are similar to those of the parent rocks. The HREE depletion and ion exchange phase of all the samples are relatively enriched. The ion exchange phase is light and heavy rare earth Together enrichment in the B2 in. Based on this speculation, granite in the brown curtain stone, stone and other easy to weathered rare earth minerals for the ion exchange phase rare earth provides the main source of zircon, xenotime and other weathered rare earth minerals The formation of residual and supergene rare earth minerals enriched all-phase HREE, the ion exchange phase was light and the fractionation of heavy rare earth elements changed with the degree of weathering.